Embedded Robotics: Mobile Robot Design and Applications with Embedded Systems

427 Pages·2003·36.839 MB·English

by  Thomas Bräunl (auth.)

Embedded Robotics
Springer-Verlag Berlin Heidelberg GmbH
Thomas Braunl
EMBEDDED ROBOTICS
Mobile Robot Design
and Applications
with Embedded Systems
With 203 Figures, 33 in color, and 24 Tables
Springer
Thomas Braunl
School of Electrical, Electronic
and Computer Engineering
The University of Weste m Australia
35 Stirling Highway
Crawley, Perth, W A 6009
Australia
Cataloging-in-Publication Data applied for
Bibliographic information published by the Deutsche Bibliothek
Die Deutsche Bibliothek lists this publication in the Deutsche Nationalbibliografie;
detailed bibliographic data is available in the Internet at <http://dnb.ddb.de>
ACM Subject Classification (1998): I.2.9, C.3
ISBN 978-3-662-05101-6 ISBN 978-3-662-05099-6 (eBook)
DOI 10.1007/978-3-662-05099-6
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© Springer-Verlag Berlin Heidelberg 2003
Originally published by Springer-Verlag Berlin Heidelberg New York in 2003
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PREFACE
I
t all started with a new robot lab course I had developed to accompany my
robotics lectures. We already had three large, heavy, and expensive
mobile robots for research projects, but nothing simple and safe, which we
could give to students to practice on for an introductory course.
We selected a mobile robot kit based on an 8-bit controller, and used it for
the first couple of years of this course. This gave students not only the enjoy
ment of working with real robots but, more importantly, hands-on experience
with control systems, real-time systems, concurrency, fault tolerance, sensor
and motor technology, etc. It was a very successful lab and was greatly
enjoyed by the students. Typical tasks were, for example, driving straight,
finding a light source, or following a leading vehicle. Since the robots were
rather inexpensive, it was possible to furnish a whole lab with them and to con
duct multi-robot experiments as well.
Simplicity, however, had its drawbacks. The robot mechanics was unreli
able, the sensors were quite poor, and extendability and processing power were
very limited. What we wanted to use was a similar robot at an advanced level.
The processing power had to be reasonably fast, it should use precision motors
and sensors, and - most challenging - the robot had to be able to do on-board
image processing. This had never been accomplished before on a robot of such
a small size (about 12cm x 9cm x 14cm). Appropriately, the robot project was
called "EyeBot". It consisted of a full 32-bit controller ("EyeCon"), interfacing
directly to a digital camera ("Eye Cam") and a large graphics display for visual
feedback. A row of user buttons below the LCD was included as "soft keys" to
allow a simple user interface, which most other mobile robots lack. The
processing power of the controller is about 1,000 times faster than for robots
based on most 8-bit controllers (25MHz processor speed vs. IMHz, 32-bit data
width vs. 8-bit, compiled C code vs. interpretation) and this does not even take
into account special CPU features like the "time processor unit" (TPU).
The EyeBot family today includes several driving robots with differential
steering, tracked vehicles, omni-directional vehicles, balancing robots, six-leg
ged walkers, biped android walkers, a flying robot, and a simulation system
("EyeSim"). EyeCon controllers are used in several other projects, with and
v
Preface
without mobile robots. Numerous universities use EyeCons to drive their own
mobile robot creations. We use boxed EyeCons for experiments in a second
year course in Embedded Systems as part of the Electrical Engineering, Infor
mation Technology, and Mechatronics curriculums. And one lonely EyeCon
controller sits on a pole on Rottnest Island offthe coast of Western Australia,
taking care of a local weather station.
Acknowledgements
While the controller hardware and robot mechanics were developed commer
cially, several universities and numerous students contributed to the EyeBot
software collection. The universities involved in the EyeBot project are:
University of Stuttgart, Germany
University of Kaiserslautern, Germany
Rochester Institute of Technology, USA
The University of Auckland, New Zealand
The University of Manitoba, Winnipeg, Canada
The University of Western Australia, Perth, Australia
The author would like to thank the following students, technicians, and
colleagues: Gerrit Heitsch, Thomas Lampart, J6rg Henne, Frank Sautter, Elliot
Nicholls, Joon Ng, Jesse Pepper, Richard Meager, Gordon Menck, Andrew
McCandless, Nathan Scott, Ivan Neubronner, Waldemar Spadt, Petter
Reinholdtsen, Birgit Graf, Michael Kasper, Jacky Baltes, Peter Lawrence, Nan
Schaller, Walter Bankes, Barb Linn, Jason Foo, Alistair Sutherland, Joshua
Petitt, Axel Waggershauser, Alexandra Unkelbach, Martin Wicke, Tee Yee
Ng, Tong An, Adrian Boeing, Courtney Smith, Nicholas Stamatiou, Jonathan
Purdie, Jippy Jungpakdee, Daniel Venkitachalam, Tommy Cristobal, Sean
Ong, and Klaus Schmitt.
Thanks for proofreading the manuscript and numerous suggestions go to
Adrian Boeing, Michael Kasper, Sandra Passamani, Joshua Petitt, Klaus
Schmitt, Anthony Zaknich, and everyone at Springer-Verlag.
Contributions
A number of colleagues and former students contributed to this book. The
author would like to thank everyone for their effort in putting the material
together.
JACKY BALTES The University of Manitoba, Winnipeg, contributed to the
section on PID control and to the sections on camera inter
faces,
ADRIAN BOEING The University of Western Australia, Perth, authored the
chapter on the evolution of walking gaits and coauthored the
chapter on genetic algorithms,
VI
Preface
CHRISTOPH BRAUNSCHADEL FH Koblenz, contributed data plots to the sec
tions on on/off control and PID control,
BIRGIT GRAF Fraunhofer IP A, Stuttgart, coauthored the chapter on robot
soccer,
YVES HWANG The University of Western Australia, Perth, coauthored the
chapter on genetic programming,
PHILIPPE LECLERCQ The University of Western Australia, Perth, contributed to
the section on color segmentation,
JOSHUA PETITT The University of Western Australia, Perth, contributed to
the section on DC motors,
KLAUS SCHMITT University of Kaiserslautern, coauthored the chapter on the
RoBIOS operating system,
ALISTAIR SUTHERLAND The University of Western Australia, Perth, co
authored the chapter on balancing robots,
NICHOLAS TAY DSTO, Canberra, coauthored the chapter on map genera
tion,
DANIEL VENKITACHALAM The University of Western Australia, Perth, coau
thored the chapters on genetic algorithms and behavior
based systems and contributed to the chapter on neural net
works,
AxEL W AGGERSHAUSER University of Kaiserslautern, contributed to the sec
tion on simulation parameter files.
Additional Material
Hardware and mechanics of the "EyeCon" controller and various robots ofthe
EyeBot family are available from JOKER ROBOTICS and its distributors:
http://joker-robotics.com
All system software discussed in this book, the RoBIOS operating system,
C/C++ compilers for Linux and Windows, system tools, image processing
tools, simulation system, and a large collection of example programs are avail
able free from:
http://robotics.ee.uwa.edu.au/eyebot/
Lecturers who adopt this book for a course can receive a full set of the
author's course notes (PowerPoint slides), tutorials, and labs from this website.
And finally, if you have developed some robot application programs you
would like to share, please feel free to submit them to our website.
Perth, Australia, June 2003 Thomas Braunl
VII
CONTENTS
PART I: EMBEDDED SYSTEMS
1 Introduction 3
1.1 Mobile Robots ................................................... 4
1.2 Embedded Controllers ............................................. 7
1.3 Interfaces ...................................................... 10
1.4 References ..................................................... 13
2 Programming Tools 15
2.1 System Installation ............................................... 15
2.2 Compiler for C and C++ .......................................... 16
2.3 Assembler ..................................................... 18
2.4 Debugging ..................................................... 20
2.5 Download and Upload ............................................ 22
2.6 References ..................................................... 23
3 RoBIOS Operating System 25
3.1 RoBIOS Structure ............................................... 25
3.2 Monitor Program ................................................ 28
3.3 System Function and Device Driver Library ........................... 34
3.4 Hardware Description Table ....................................... 36
3.5 Boot Procedure ................................................. 40
3.6 References ..................................................... 41
4 Multitasking 43
4.1 Cooperative Multitasking ......................................... 43
4.2 Preemptive Multitasking .......................................... 45
4.3 Synchronization ................................................. 47
4.4 Scheduling ..................................................... 51
4.5 Interrupts and Timer-Activated Tasks ................................ 54
4.6 References ..................................................... 56
5 Sensors 57
5.1 Sensor Categories ............................................... 58
5.2 Binary Sensor. .................................................. 59
5.3 Analog vs. Digital Sensors ........................................ 59
5.4 Shaft Encoder ................................................... 60
5.5 AID Converter .................................................. 62
IX
Contents
5.6 Position Sensitive Device ......................................... 62
5.7 Compass ....................................................... 65
5.8 Gyroscope, Accelerometer, Inclinometer ............................. 67
5.9 Digital Camera .................................................. 70
5.10 References..................................................... 81
6 }\ctuators 83
6.1 DC Motors ..................................................... 83
6.2 H-Bridge ...................................................... 86
6.3 Pulse Width Modulation .......................................... 88
6.4 Stepper Motors .................................................. 90
6.5 Servos ........................................................ 91
6.6 References ..................................................... 92
7 Control 93
7.1 On-Off Control ................................................. 93
7.2 PID Control .................................................... 98
7.3 Velocity Control and Position Control .............................. 104
7.4 Multiple Motors - Driving Straight ................................ 105
7.5 V-Omega Interface ............................................. 108
7.6 References .................................................... 110
8 Real-Time Image Processing 111
8.1 Camera Interface ............................................... 111
8.2 Auto-Brightness ................................................ 113
8.3 Edge Detection ................................................. 114
8.4 Motion Detection ............................................... 116
8.5 Color Space ................................................... 117
8.6 Color Object Detection .......................................... 119
8.7 Image Segmentation ............................................ 124
8.8 Image Coordinates versus World Coordinates ........................ 126
8.9 References .................................................... 128
9 Wireless Communication 131
9.1 Communication Model .......................................... 132
9.2 Messages ..................................................... 134
9.3 Fault-Tolerant Self-Configuration .................................. 135
9.4 UserInterface and Remote Control. ................................ 137
9.5 Sample Application Program ...................................... 140
9.6 References ........................................ ............ 141
x
Contents
PART II: MOBILE ROBOT DESIGN
10 Driving Robots 145
10.1 Single Wheel Drive ............................................. 145
10.2 Differential Drive ............................................... 146
10.3 Tracked Robots ................................................ 150
10.4 Synchro-Drive ................................................. 151
10.5 Ackennann Steering ............................................ 153
10.6 Model Cars as Robots ........................................... 154
10.7 Localization ................................................... 155
10.8 Navigation .................................................... 160
10.9 Software Architecture ........................................... 167
10.10 References .................................................... 168
11 Omni-Directional Robots 171
11.1 Mecanum Wheels .............................................. 171
11.2 Omni-Directional Kinematics ..................................... 172
11.3 Omni-Directional Robot Design ................................... 175
11.4 Driving Program ............................................... 175
11.5 References .................................................... 177
12 Balancing Robots 179
12.1 Simulation .................................................... 179
12.2 Inverted Pendulum Robot ........................................ 180
12.3 Double Inverted Pendulum ....................................... 183
12.4 References .................................................... 184
13 Walking Robots 187
13.1 Six-Legged Robot Design ........................................ 187
13.2 Biped Robot Design ............................................. 190
13.3 Sensors for Walking Robots ...................................... 193
13.4 Static Balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
13.5 Dynamic Balance ............................................... 197
13.6 References .................................................... 202
14 Autonomous Planes 205
14.1 Application ................................................... 205
14.2 Control System and Sensors ...................................... 208
14.3 Flight Program ................................................. 209
14.4 References .................................................... 213
15 EyeSim Simulator 215
15.1 Mobile Robot Simulators ......................................... 215
15.2 EyeSim UserInterface ........................................... 216
15.3 Sensor-Actuator Modeling ....................................... 218
15.4 Multiple Robot Simulation ....................................... 220
15.5 Sample Application ............................................. 221
15.6 Environment Representations ..................................... 222
15.7 Parameter Files ................................................ 225
15.8 References .................................................... 229
XI